Transport in Plants II

As plant physiology increased steadily in the latter half of the 19th century, problems of absorption and transport of water and of mineral nutrients and problems of the passage of metabolites from one cell to another were investigated, especially in Germany. JUSTUS VON LIEBIG, who was born in Darmstadt in 1803, founded agricultural chemistry and developed the techniques of mineral nutrition in agricul­ ture during the 70 years of his life. The discovery of plasmolysis by NAGEL! (1851), the investigation of permeability problems of artificial membranes by TRAUBE (1867) and the classical work on osmosis by PFEFFER (1877) laid the foundations for our understanding of soluble substances and osmosis in cell growth and cell mechanisms. Since living membranes were responsible for controlling both water movement and the substances in solution, "permeability" became a major topic for investigation and speculation. The problems then discussed under that heading included passive permeation by diffusion, Donnan equilibrium adjustments, active transport processes and antagonism between ions. In that era, when organelle isolation by differential centrifugation was unknown and the electron microscope had not been invented, the number of cell membranes, their thickness and their composition, were matters for conjecture. The nature of cell surface membranes was deduced with remarkable accuracy from the reactions of cells to substances in solution. In 1895, OVERTON, in U. S. A. , published the hypothesis that membranes were probably lipid in nature because of the greater penetration by substances with higher fat solubility.

Contenu

of Part A.- I. Theoretical and Biophysical Approaches.- 1. The Structure of Biological Membranes.- 1. Introduction.- 2. The Lipid-Protein Sandwich.- 3. The Liquid Amphiphilic Layer.- 2. Water Relations of Plant Cells.- 1. Introduction.- 2. Water Potential.- 3. The "Static" Water Relations of a Single Plant Cell.- 4. Transport of Water across Cell Membranes.- 5. Conclusion.- 3. Membrane Transport: Theoretical Background.- 1. Introduction.- 2. Origins of Equations.- 3. Equilibrium Equations (Class A).- 4. Rate Equations (Class A: Mechanism-Independent).- 5. Rate Equations (Class B: Mechanism-Dependent).- 4. Electrical Properties of Plant Cells: Methods and Findings.- 1. Methods.- 1.1 The Potential Difference.- 1.2 What an Inserted Microelectrode Actually Measures.- 1.3 Measurement of Membrane Resistance.- 1.4 The Control of Membrane Potential Difference by Voltage Clamping.- 1.5 Electrical Capacitance of Membranes.- 2. Electrical Properties of Cells-A Perspective.- 2.1 Potential Difference.- 2.2 Conductance.- 2.3 Membrane Capacitance.- 2.4 The Action Potential.- 2.5 Testing for Active and Passive Transport.- 2.6 Electrogenic Effects-the PD as a Function of Metabolic Activity.- 2.7 Electrical Properties and Membrane Structure.- 2.8 Unusual Measurements.- 2.9 Effects of Uncouplers and Antibiotics.- 2.10 Visible, UV and Ionizing Radiations.- 5. Measurement of Fluxes across Membranes.- 1. Introduction.- 2. Theoretical Basis of Flux Estimation.- 3. The Effect of the Free Space on Flux Measurements.- 4. Practical Estimation of Fluxes from Tracer Elution Measurements.- 5. Applications of Flux Analysis.- 6. Conclusions.- II. Particular Cell Systems.- 6. Transport in Algal Cells.- 1. Introduction.- 2. Algal Structure in Relation to Transport.- 3. Elemental Composition of Algae.- 4. Experimental Materials and Methods.- 5. Electrochemical Driving Forces in Algal Cells and Ionic Contents.- 6. Fluxes of Electrolytes.- 7. Transport of Non-Electrolytes.- 8. Conclusions and Evolutionary Speculations.- 7. Transport in Fungal Cells.- 1. Introduction.- 2. Potassium-Hydrogen or -Sodium Exchange System: Neurospora crassa and Saccharomyces cerevisiae.- 3. Ammonium and Methyl Ammonium Transport.- 4. Bivalent Cation Transport: Saccharomyces cerevisiae.- 5. Phosphate Transport.- 6. Transport of Sulfate and Other Sulfur Compounds.- 7. Amino Acid Transport.- 8. Monosaccharide Transport.- 9. Uptake of Di-and Trisaccharides.- 10. Ion and Proton Movements Accompanying Organic Solute Absorption.- 8. Transport in Cells of Storage Tissues.- 1. Introduction.- 2. Material.- 3. Red Beet (Beta vulgaris L.).- 4. Carrot (Daucus carota L.).- 5. Potato (Solanum tuberosum L.).- 6. Conclusion.- III. Regulation, Metabolism and Transport.- 9. Transport and Energy.- 1. Introduction.- 2. Particular Energy Source for Particular Transport Mechanism.- 3. Coupling between Sources of Metabolic Energy and Transport Mechanisms.- 4. Energy Requirement for Ion Transport.- 10. ATPases Associated with Membranes of Plant Cells.- 1. Introduction.- 2. Difficulties in Establishing a Role for ATPases in Ion Transport.- 3. ATPase Activity of Soluble Fractions.- 4. ATPase Activity of Membrane Fractions.- 5. Evidence for ATPase Involvement in Cation Absorption by Roots.- 6. Summary.- 11. Negative Feedback Regulation of Transport in Cells. The Maintenance of Turgor, Volume and Nutrient Supply.- 1. Introduction.- 2. Some Elementary Properties of Control Systems.- 3. Experimental Observations.- 3.1 Control of the Total Number of Osmotically Active Particles in Cells.- 3.2 Control of the Uptake and Accumulation of Specific Substances in Plant Cells.- 4. Mechanisms of Negative Feedback Regulation.- 5. Interrelations between Systems Regulating Transport.- 12. H+ Transport and Regulation of Cell pH.- 1. Introduction.- 2. Effects of Metabolism on the pH of Cells and Their Surroundings.- 3. Biophysical Implications of H+ Transport.- 4. Models for H+ Transport.- 5. H+ Fluxes and the Regulation of Solute Accumulation.- 6. H+ Transport in Morphogenesis.- 7. Conclusions: the Evolution of H+ Transport.- 13. Ion Absorption and Carbon Metabolism in Cells of Higher Plants.- 1. Introduction.- 2. Regulation of Carboxylate Metabolism during Ion Uptake.- 3. Ion Concentration and Enzyme Activity.- 4. Modification of Enzymic Activity and Properties in Relation to Ionic Environment.- 5. Regulation of Internal Ionic Environment; Osmotic and Metabolic Responses.- 6. Conclusions.- Author Index (Part A).- Symbols, Units, and Abbreviations.- Subject Index (Part A and B) (after p. 400).